Process and apparatus for drying a plurality of dip-coated medicaments

ABSTRACT

A process and apparatus for the gelatin coating of medicaments which includes a continuous conveyer system to advance a plurality of pallets through a loading station, at least one dipping station, at least one dryer station, a reorientation station and an unloading station. Medicaments to be coated are loaded into pallets at the loading station and advanced to the first dipping station where a vacuum is applied to secure the medicament to the pallet. The pallet is inverted and a first portion of each of the medicaments is dipped into a coating mixture. The pallet is then returned to its upright position, the vacuum is removed and the coating is dried. The medicaments are then transferred from the first pallet to a second pallet by a reorientation mechanism. The second pallet is then advanced to a second dipping station which operates in the same manner as the first dipping station. The second pallet is advanced through the dryer station and the fully coated medicaments are ejected from the pallet into a container. The pallets used to hold the medicaments include a plate-like support member, on which rests a flexible mat having a rectangular array of receptacles including compliant diaphragm portions such that when a vacuum is applied to the pallet, the medicaments are secured thereto. The drying means includes air directing plates having sinusoidal rows of air directing apertures under which the medicaments to be dried are passed.

This application is a divisional of application Ser. No. 08/900,225filed on Jul. 24, 1997, U.S. Pat. No. 5,942,034.

FIELD OF THE INVENTION

The present invention relates to a process and apparatus for the gelatincoating of medicaments.

BACKGROUND OF INVENTION

Many products, including prescription drugs, over the counter drugs(e.g., analgesics) and vitamins, come in a solid dosage (i.e.,“medicament”) form. Two common shapes for these medicaments are referredto as “tablets” and “caplets”. Tablets are generally disc-shaped havinga diameter that is greater than their height. Caplets are elongatedshapes having a longitudinal axis that is greater than the greatestthickness of the medicament along the longitudinal axis, typically byapproximately 2.5 times. Both usually include rounded ends and edges anda flat surface corresponding to the walls of the die in which themixture of ingredients are pressed into the particular solid dosageform. The flat area is sometimes referred to as a sidewall and can forma corner or edge relative to the two sides on opposite sides of thesidewall.

A common problem with both caplets and tablets (collectively“medicaments”) is the texture or feel of their surfaces. Without anyouter coating, both forms have a “chalky” texture formed by thecompressed mixture. Research has established that some people believeuncoated medicaments are difficult to swallow. Research also has found,however, that people believe that medicaments having a gelatin orsimilar coating are significantly easier to swallow. Accordingly, manysuch processes have been developed and are known in the art.

One such process, disclosed in U.S. Pat. No. 599,865, utilizes a bar orplate which has been coated with a cleanly separable adhesivepreparation, such as a combination of beeswax and rosin. Medicaments tobe coated are pressed onto the adhesive and partially dipped into acoating mixture. The medicaments may then be dried and pressed onto asecond adhesive coated bar or plate so that the remaining portions ofthe medicaments may be dipped.

U.S. Pat. No. 540,538 discloses a machine for dipping medicaments whichutilizes a plate having countersunk holes to retain tablets by theapplication of a vacuum through the holes. The plate is placed over avacuum box and medicaments are placed in each hole. A vacuum is thenapplied and the box and plate are inverted, thereby allowing themedicaments to be dipped in a coating bath. Once the medicaments havebeen dipped, the box is returned to its upright position, the vacuum isremoved and the plate is manually removed, with the medicaments inplace, to allow drying of the coating. After drying, the medicaments maybe transferred onto a second plate with their uncoated sides exposed bymanually placing the second plate over the medicaments contained on thefirst plate and flipping the two plates over. The uncoated sides maythen be coated as described above.

Another process, disclosed in Japanese Patent Publication No. 41-13997,utilizes rigid tubes to retain tablets on their ends by the applicationof a suction force through the tube center. After dipping the tablets toapproximately their midpoints and drying, the tablets are inverted andtransferred onto opposing tubes. The vacuum is then switched from thefirst set of tubes to the second thereby exposing the uncoated portionsof the tablets to be dipped. A drawback of this system is that no meansis provided to easily center the tablets on the tubes.

U.S. Pat. No. 2,373,721 refers to a system for coating medicaments inwhich the medicaments are held over a coating tank in an invertedorientation by suction tubes. Cups slightly larger than the individualmedicaments are then raised from an initial position, submerged in thecoating, to immerse the individual medicaments in coating materialcontained within the cups.

U.S. Pat. No. 4,965,089 refers to the use of a caplet holding platehaving sets of caplet gripping collets on both sides thereof. Caplets,initially disposed on one side of the plate, are dipped in a gelatincoating on one end then pushed through the plate so that the other sideof the caplet may be coated. The disadvantages of such a system are thatthe caplet holding plate is not suitable for coating tablets having aheight substantially less than their diameter. In addition, the coatedsurface may be damaged when pushed through the collet to the other sideof the caplet holding plate.

U.S. Pat. No. 5,228,916, refers to the use of moveable vacuum tubes,which extend through a carrier plate, to secure tablets to be dipped.Such a process is not, however, well suited for coating caplets whoseends may not be readily secured to a vacuum tube. In addition, the useof multiple moveable vacuum tubes makes it difficult to maintain thetablets centered on the vacuum tubes in a level plane parallel with thesurface of the coating in which the tablet is to be dipped. It is,therefore, difficult to obtain a level transition line when coatingtablets with more than one color coating.

Therefore, there exists a need for a medicament coating system which maybe easily adapted to coat medicaments of different sizes and shapes andwhich produces a uniform coating with no damage to the finished product.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a methodand apparatus for coating medicaments to produce a uniform, undamagedcoating.

A further object of the present invention is to provide a method andapparatus for coating medicaments which may be easily adapted to coatmedicaments of different sizes and shapes.

Still another object of the present invention is to provide an apparatusto secure medicaments to a pallet in a level orientation such that thepallet may be inverted and the medicaments dipped in a coating mixture.

Yet another object of the present invention is to provide a method andapparatus to evenly and quickly dry a coating once it has been appliedto a medicament.

The above and other objects are achieved in accordance with a firstaspect of the present invention by an apparatus comprising a continuousconveyer system to advance a plurality of pallets through the sequenceof stations at which the steps necessary to dip and coat each side of amedicament with a coating are performed. The stations of the systeminclude a loading station, at least one dipping station, at least onedryer station, a reorientation station and an unloading station.

Medicaments to be coated are loaded into pallets with a first portion ofthe medicaments exposed at the loading station. The pallets are orientedin an upright position so that the medicaments extend above the surfaceof the pallet. After a pallet is loaded, it proceeds along the conveyerto the first dipping station. At the first dipping station, a vacuum isapplied to the pallet to secure the medicaments to the pallet and thepallet to the end effector tooling of a robot arm. The pallet is theninverted and the first exposed portion of each of the medicaments isdipped into a bath to coat the exposed end. The dipping step has a firstdipping profile of insertion rate and depth, dwell time in the bath, andremoval rate to control the coating on the medicament. Preferably, thebath is a gelatin or a gelatinous bath for gel coating the medicament.

After the dipping step, the pallet is returned to its upright positionon the conveyer, and the vacuum is removed. The pallet is then advancedto the dryer station, where the coating is dried. The dryer stationincludes a series of conveyors similar to those which transport thepallets between the different stations. The dryer conveyors transportthe pallets through at least one, and preferably two drying rooms. Thedrying rooms have a controlled environment and vertical air flow plenumsover each conveyor section. The air plenums are disposed horizontallyover the path of the pallets and include rows of air directingapertures, preferably in a sinusoidal arrangement, running in thedirection of product flow for directing a flow of air onto themedicaments. When the pallets exit the dryer station, the coating on thefirst exposed portion of the medicaments has been fully dried.

The pallets are then passed to the reorientation station where thepartially coated medicaments are transferred from the first pallet to asecond pallet to expose the uncoated ends. The second pallet isidentical to the first pallet. The transfer is accomplished in thereorientation station by indexing the first pallet under the secondpallet, which is in a face-down orientation. The two pallets are thenurged against a transfer plate to form a sandwich, which is then rotated180° to invert the pallets so that the medicaments free-fall downwardfrom the first pallet, through apertures in the transfer plate, into themedicament receptacles of the second pallet, leaving a second o portionof the medicaments exposed. The first pallet, now empty and in a facedown orientation, remains in the reorientation station to be the“second” pallet for the next full pallet entering the reorientationstation.

The second pallet, now loaded, is then ejected or withdrawn from thereorientation station and advanced to a second dipping station. Thesecond dipping station operates in the same manner as the first dippingstation except that it may have a second dipping profile that isdifferent from the first dipping profile. Preferably, the dippingprofiles are identical. Thus, the second exposed portion of themedicaments is dipped in the same manner as the first portion.Preferably, the second dipping station has a bath of similar material tothe bath of the first dipping station, more preferably a gelatin orgelatinous bath of the same color or a different color as that of thefirst dipping station. It also should be understood that the first andsecond dipping stations, in one embodiment, could use a common bath andin another embodiment, could use baths of different types of materials.

After the second coating has been applied, the second pallet is advancedthrough the dryer station in the same direction as occurred after thefirst coating. At the exit of the dryer station, the medicaments arefully dried and are sent to the unloading station where the coatedmedicaments are ejected from the pallet. It should be understood thatthe conveyor system can be a series or a plurality of conveyers thattransfer the pallets along and between the stations.

In a second aspect of the invention, an apparatus to hold themedicaments to be coated is provided. In one embodiment, the apparatuscomprises pallets that include a plate-like support member, on whichrests a resilient and deformable mat having a rectangular array ofmedicament receptacles. The surface of the support member that abuts themat contains a matrix of very fine grooves that provide channels forcommunication of a vacuum. These channels are connected to centrallylocated holes or apertures, e.g., three, extending through the supportmember. These holes can be coupled to a vacuum source, e.g., in the endeffector of a robot arm capable of engaging the pallets and invertingthem for dipping in the bath.

One such mat is configured with receptacles for medicaments that aretablets. This mat has raised hollow tubular portions that provide holesthrough which the vacuum can act to hold tablets seated on the tubularportion. In this embodiment, each tubular portion holds only one tabletat a time by resting the tablet upon the top end portion of the tube.The mat also includes portions that project upwardly from the mat,adjacent to and around the upwardly extending tubular portions. Theseprojections serve as rests and guides to support and center each of thetablets on a tubular portion in the absence of any vacuum holding thetablet thereon. These projections are mounted on compliant diaphragmportions of the mat. When the vacuum is applied to secure the tablet tothe tubular portion and hence the mat, the diaphragm portions flex andthe support projections are deflected away from the tablet, whichremains centrally contained within the receptacle. When the vacuum isremoved, the diaphragms return to their normal position and theprojections will support the tablet so that it will not fall off thetubular portion.

Another such mat is configured for medicaments that are caplets. In thisembodiment, the medicament receptacles of the caplet mat do not haveholes through the mat, but instead, include small compartments formed byraised portions in the mat. These raised portions form the walls of thecaplet-holding compartments. These walls are mounted on compliantdiaphragm portions of the mat such that when the vacuum is applied, thediaphragms flex and the walls are deflected toward the caplet containedwithin the receptacle. This action results in securing the caplets tothe mat. It also results in straightening the caplets in the pallet,thereby to provide them with a relatively uniform orientation fordipping.

In another aspect of the present invention, an improved apparatus fordrying the coated medicaments is provided. The improved drying meansincludes air directing plates under which the medicaments to be driedare passed. Each air directing plate has at least one row of airdirecting apertures arranged in a sinusoidal layout running in thedirection of product flow. Preferably, the air directing apertures aredirected normal to the plane of the pallets and there is approximatelyone row of apertures corresponding to medic parallel with, each row ofmedicaments on the pallets passing thereunder. An air plenum is used toforce air through the air directing plates as the coated pallets passthereunder. This results in a wash of air that swirls around the coatedmedicament as the medicament moves through the drying section, andprovides an effective drying of the coated medicaments, particularlygelatin coated medicaments.

These and other objects, features and advantages of the presentinvention will be apparent and fully understood from the followingdetailed description of the preferred embodiments, taken in connectionwith the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be better understood when considered with thefollowing drawings in which like reference numerals refer to likeelements and in which:

FIG. 1 is a top view of the system for the dip coating of medicaments inaccordance with a preferred embodiment of the present invention;

FIG. 2 is an exploded perspective view of a pallet in accordance with apreferred embodiment of the present invention;

FIG. 3 is a top view of the support member of the pallet of FIG. 2;

FIG. 3A is a partial top view of the grooves of the support member ofFIG. 3;

FIG. 3B is a partial cross-sectional view of the grooves of the supportmember of FIG. 3;

FIG. 4 is a perspective view of a tablet mat and support member inaccordance with a preferred embodiment of the present invention;

FIG. 5 is a top view of the tablet mat of the pallet of FIG. 4;

FIG. 6 is a partial cross-sectional view of the tablet mat and supportmember of FIG. 4;

FIG. 6A is a partial cross-sectional view of the tubular portion of thetablet mat of FIG. 6;

FIG. 7 is a partial cross-sectional view of the tablet mat and supportmember of FIG. 4 with a vacuum being applied by the end effector toolingin accordance with a preferred embodiment of the present invention;

FIG. 8 is a perspective view of a caplet mat and support member inaccordance with a preferred embodiment of the present invention;

FIG. 9 is a top view of the caplet mat of the pallet of FIG. 8;

FIG. 10 is a partial cross-sectional view of the caplet mat and supportmember of FIG. 8;

FIG. 11 is a partial cross-sectional view of the caplet mat and supportmember of FIG. 8 with a vacuum being applied by the end effector toolingin accordance with a preferred embodiment of the present invention;

FIG. 12 is a side elevational view of the loading station of the presentinvention;

FIG. 13A is a front elevational view of the caplet drop tube of thepresent invention;

FIG. 13B is a side elevational view of the caplet drop tube of FIG. 13A;

FIG. 13C is a top view of the caplet drop tube of FIG. 13A;

FIG. 14A is a partial cross-sectional top view of a caplet being loadedinto a caplet mat by a caplet drop tube of the present invention;

FIG. 14B is an elevational view of a caplet being loaded into a capletmat by a caplet drop tube of the present invention;

FIG. 15A is a front elevational view of the tablet drop tube of thepresent invention;

FIG. 15B is a side elevational view of the tablet drop tube of FIG. 15A;

FIG. 15C is a top view of the tablet drop tube of FIG. 15A;

FIG. 16 is a top view of the dipping stations and automatic drawdownsystem of the present invention;

FIG. 17 is a top view of one of a dipping station of the presentinvention;

FIG. 18 is a top view of the capture station and end effector tooling ofFIG. 17;

FIG. 19 is a cross-sectional view of the end effector tooling andcentering plate used to center caplets at a dipping station of thepresent invention;

FIG. 20 is an cross-sectional view of caplets being dipped at a dippingstation of the present invention;

FIG. 21 is an cross-sectional view of tablets being dipped at a dippingstation of the present invention;

FIG. 22 is a partial top view of a dryer air plenum plate of the presentinvention;

FIG. 23 is a schematic diagram of the process air flow handling systemof the present invention;

FIG. 24 is a side elevational view of the reorientation station of thepresent invention;

FIG. 25 is a front cross-sectional view of the reorientation station ofFIG. 24 configured for caplets;

FIG. 26 is a front cross-sectional view of the reorientation station ofFIG. 24 configured for tablets;

FIG. 27 is a top view of the unloading station of the present invention;

FIG. 28 is a side elevational view of the unloading station of FIG. 27;and

FIG. 29 is schematic process diagram of the automatic drawdown system(ADS) of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The system for coating medicaments according to the present inventioncomprises two major sections. One section, the Carrier Handling System(CHS), is shown on the right side of FIG. 1 and the second section,known as the Automatic Drawdown System (ADS), is shown on the left handportion of FIG. 1.

In the preferred embodiment, the medicaments are dip coated with agelatinous or gelatin material, as is discussed below. However, itshould be understood that this invention is applicable to dip coatingmedicaments with materials other than gelatin and gelatinous materials,as will be appreciated by a person of ordinary skill in the art.

Further, in the preferred embodiment, the medicament is preferablyacetylsalicylic acid (commonly known as ASA and by its trademarkASPIRIN) and preferably has been spray-coated with a subcoating. Itshould, nevertheless, be understood that the present invention isapplicable to dip coating medicaments having a composition other thanASA and the particular disclosed subcoating. For example, otheranalgesics such as acetaminophen, ibuprofin, ketoprofin and combinationsthereof, alone or together with one or more other active ingredientssuch as decongestants, antihistamines, expectorants, caffeine, sleepaides, as well as inactive ingredients and excipients, as well as otherover the counter and prescription or ethical pharmaceutical products ornutritionals could be used.

The currently preferred subcoating is applied in a conventional one-stepspraying operation and consists of a water soluble film former(hydroxypropyl methylcellulose (HPMC)), a slightly soluble plasticizer(triacetin), and a hydrophobic surfactant (sorbitan trioleate). Asuitable formulation for the subcoating is given in Table 1.

TABLE 1 SUBCOATING FORMULATION Raw Material % of Raw Materialhydroxypropyl methylcellulose (HPMC) 82.12 triacetin 16.42 sorbitantrioleate  1.46

After the subcoating has been applied, the medicaments are “conditioned”by placing them in a bin and exposing them to compressed air. In thepreferred embodiment, the bin is closed, but not sealed and includes oneor more air distribution wands to which a compressed air source may beattached. Each distribution wand is essentially a pipe having aplurality of holes along its length to distribute the compressed airthroughout the bin. The compressed air is at ambient temperature andsupplied to the bin so as to provide a positive pressure in the bin. Atthe end of approximately 24 hours of exposure to the compressed air, themedicaments are sampled and the moisture content analyzed. Provided themoisture content is verified to be below a predetermined level (i.e.,1.5%) the medicaments are sent to the loading station to be loaded ontothe pallets as described below.

The Carrier Handling System (CHS)

The major components of the CHS, as illustrated in FIG. 1, are a loadingstation 10, a first dipping station 20, a dryer station 30, areorientation station 50, a second dipping station 60, and an unloadingstation 70. Medicaments are transported between the above stations by aconveyer system 100. The conveyer system 100 is comprised of flexibleplastic links and is designed for 24 hour a day operation. Preferably,the conveyor system 100 is actually a series of separate conveyor beltsthat, together with the various operating stations, form a continuouspath. One suitable conveyor system is to use the known conveyor systemsfor transporting cases of carbonated beverages.

The medicaments are carried on the conveyer system 100 by speciallydesigned pallets 200 which are adapted to hold the medicaments wheninverted through the application of a vacuum.

The Pallets

Referring to FIGS. 2-11, the pallets 200 used in the system of thecurrent invention to transport the medicaments between stations includea plate-like support member 210, on which rests a mat 270 (or 240)having a rectangular array of receptacles 272 (or 230) designed toreceive the medicaments. Because of the differences in geometry, thetablet mats 240 (FIGS. 4-7) differ in design from the caplet mats 270(FIGS. 2 and 8-11), but in both cases the support member 210 isidentical. In the preferred embodiment, the mats 240 and 270, are formedof rubber, however, other resilient, impermeable materials may be used,e.g., silicone.

Referring to FIGS. 2-3B, the support member 210 is preferably arectangular tray having a rim 212 around its perimeter and a flatreceiving surface 214 within the area defined by the rim 212 forreceiving the mat 240 or 270. The mat 240 or 270 rests on the receivingsurface 214 of the support member 210. A rib 216 is integrally formed onthe receiving surface 214 of the support member 210 just inside the rim212. Rib 216 extends around the perimeter of the support member 210 andfits within a corresponding sealing channel 232 formed in the mat toprovide a substantially air tight seal therebetween. (See FIGS. 6, 7, 10and 11). It is important that the mat 240 or 270 be seated squarely insupport member 210 so that the receptacles 230 or 272 are in asubstantially rectangular array of straight lines, and not curved, whichcould adversely affect the ability to fill the pallet with medicaments.This adjustment may be made by manual manipulation of the mat.

The receiving surface 214 of the support member 210, which abuts the mat240 or 270, contains a matrix of very fine grooves 218, which are formedin the process of molding the support member 210. These grooves 218provide channels for communication of a vacuum. As best seen in FIGS.3-3B, the grooves 218 of the preferred embodiment have a triangularcross-section, are approximately 0.015″ deep and 0.030″ wide, and are ina cross-hatched arrangement with approximately 0.090″ between adjacentgroves. The grooves 218 are connected to four centrally located holes220 which extend through the support member 210 to which a vacuum may beapplied.

In the preferred embodiment, the support members 210 are formed of arigid plastic, such as polycarbonate, so as to be dimensionally stablein the operating environment of the CHS and to not warp to anysignificant degree, despite repeated use and thermal cycling. It should,however, be apparent to one skilled in the art that other materials,such as steel or aluminum, could be used. In addition, other grooveconfigurations and other means of communicating the vacuum across thereceiving surface of the support member may be used so long as thesupport member 210 provides support to the mats at the requiredlocations. One example of an alternative embodiment would include raisedmembers strategically placed on the receiving surface of the supporttray to allow deflection of the diaphragm portions of the mat while, inthe case of the tablet mat, simultaneously supporting the tubularsections and allowing the vacuum to be communicated through their centerapertures. (See description of mats 240 and 270 below).

The receptacles in the tablet mat 240, illustrated in FIGS. 4-7, consistof raised tubular portions 242 that provide holes 243 through which avacuum can act. Each tubular portion 242 holds only one tablet at a timeby resting the tablet upon the top end 244 of the tubular portion 242.(See FIG. 6.) The bottom end 246 of the tubular portion 242 rests on thereceiving surface 214 of the support member 210 and is aligned with atleast one of the grooves 218 therein. Accordingly, when a vacuum isapplied to the support member 210 at holes 220, it is communicatedthrough the grooves 218 to the tubular portions 242 of the mat 240 tosecure the tablets 204 to the mat 240. (See FIG. 7). Because the bottomends 246 of tubular portions 242 are in contact with the receivingsurface 214 of the support member 210, the tubular portions 242 do notmove in a direction perpendicular to the receiving surface 214.

In the preferred embodiment, the tubular portions have an outer diameterof 0.200″ and an inner diameter of 0.120″. Thus, each tube wall isapproximately 0.040″ thick. At the top end of each tubular portion, theinner 0.030″ is angled inward at 45°. (See FIG. 6A).

The tubular portions 242 of the mat 240 are integrally connected tocompliant diaphragm portions 250 of the mat 240 at a point 248 betweenthe bottom end 246 and the top end 244 of the tubes 242. Thus, thecompliant diaphragm portions 250 are held at a distance away from thereceiving surface 214 of the support member 210. (See FIGS. 6 and 7).The compliant diaphragm portions 250 of the mat 240 are further arrangedso that each compliant diaphragm portion 250 is aligned with at leastone groove 218 in the receiving surface 214 of the support member 210.

The tablet mat 240 also includes guide portions 260 that projectupwardly from the mat (i.e., away from the support member 210), adjacentto the upwardly extending tubular portions 242. These projections 260serve as guides or stabilizing elements to center each of the tablets204 on one of the tubular portions 242. Preferably, there are four suchprojections spaced at 90° around the tubular portions, although more orfewer projections could be used. The spacing of the guide portions 260is determined by the size and shape of the tablets to be coated. In thepreferred embodiment each group of four projections defines a circulartablet receptacle with an inner diameter of 0.436″. In an alternateexample, five projections are used, particularly if the medicament has ahexagonal shape.

To ensure complete coverage of the tablets 204 by the coating, the guideportions 260 are mounted on the compliant diaphragm portions 250 of themat 240. Thus, as illustrated in FIG. 7, when the vacuum is applied tosecure the tablets 204 to the tubular portion 242, the compliantdiaphragm 250 is simultaneously drawn toward the support member 210,thereby deflecting the projections 260 radially away from the tablet 204and somewhat downwardly. This action exposes a retained tablet.

In the illustrated embodiment, the tablet receptacles 230 are arrangedin a plurality of rows 231 best seen in FIGS. 4 and 5, each spacedapproximately 0.743″ center-to-center from the adjacent row 231 ofreceptacles 230. Receptacles 230 within a row 231 are spacedapproximately 0.495″ center-to-center from the adjacent receptacles.This close spacing within each row 231 is accomplished by formingadjacent guide projections 260 as a single piece. It should, therefore,be apparent that when deflected, the shared guide projections 260 aredeflected primarily towards the adjacent row 231 of receptacles 230.

The pallet used to transport the caplets is similar to the pallet usedfor tablets. The caplet pallet employs an identical plate-like supportmember 210, on which rests a somewhat different mat 270 (shown in FIGS.2 and 8-11) having a rectangular array of receptacles 272. In this case,there are no holes through the mat 270. Instead, the receptacles consistof small compartments 272 formed by raised gripping portions 280 formedon the top surface of the mat 270. These gripping portions 280 form thewalls of the caplet-holding compartments 272.

In the preferred embodiment, the gripping portions 280 are formed byraised gripping ribs 282 which are integrally formed with and run alongthe length of the caplet mat 270. Pairs of adjacent gripping ribs 282include a plurality of gripping fingers 284, each gripping finger 284being integrally formed with one of the gripping ribs 282 and the mat270, extending toward a corresponding gripping finger 284 on theopposing gripping rib 282. These gripping fingers 284 divide the regionsbetween adjacent gripping rib pairs 282 alternately into caplet-holdingcompartments 272 and drop tube receiving compartments 274.

Referring to FIGS. 10 and 11, each gripping portion 280 is integrallyformed on a compliant diaphragm section 290 of the mat 270 which alsoforms the bottom section of the caplet-holding compartment 272. Thesecompliant diaphragm portions 290 of the mat 270 are further arranged sothat each compliant diaphragm portion 290 is aligned with at least onegroove 218 in the receiving surface 214 of the support member 210.

The compliant diaphragm portion 290 of each caplet-holding compartmentis maintained at a distance from the support member 210 by spacer ribs294 integrally formed on the support member facing surface of the mat270. Thus, as shown in FIG. 11, when suction is applied to the palletassembly, the diaphragm 290 is drawn toward the support member 210 andthe raised gripping portions 280 are deflected radially inward towardsthe caplet 206 contained within the caplet-holding compartment 272,thereby frictionally engaging (i.e., “gripping”) the caplet 206. As aresult, the array of caplets 206 in the pallet are straightened to havetheir longitudinal axes substantially all normal to the pallet receivingsurface 214. This gives a uniform orientation and results in areasonably consistent dipping from pallet to pallet.

In the preferred embodiment, the spacer ribs 294 run parallel to thegripping ribs 282 and are disposed between adjacent gripping rib pairs,although they are located on the opposite (i.e., support member facing)surface of the mat 270. In addition, the preferred embodiment includesstop ribs 298 also integrally formed on the support member facingsurface of the mat 270, parallel to the spacer ribs 294 and centrallylocated below the caplet-holding compartments 272. These stop ribs 298have a lower profile than the spacer ribs 294 and, therefore, do notcontact the receiving surface 214 of the support member 210 when thediaphragm 290 is in its undeflected state as shown in FIG. 10. However,when a vacuum is applied and the diaphragm 290 is drawn toward thesupport member 210, as illustrated in FIG. 11, the stop rib 298 contactsthe receiving surface 214 and prevents full deflection of the diaphragm290.

It can be observed that the caplet holding compartments 272 of theillustrated embodiment, like the tablet receptacles 230, are arranged ina plurality of rows 271. Further, as in the case of the tabletreceptacle rows 231, the caplet compartment rows 271 are each spacedapproximately 0.743″ center-to-center from the adjacent rows 271. Thispermits the same dryer section configuration to be used for both capletsand tablets without modification of the dryer air plenum plates 42(described below). However, because the drop tube receiving compartments274 are located between adjacent caplet compartments 272, compartments272 within a row 271 are spaced further apart than the-tabletreceptacles 230, for example, approximately 1.5″ apart center-to-centerfor 500 mg caplets.

In the case of both the tablets and the caplets, a medicament is placedin each of the receptacles by using drop tubes (described below) whichallow the medicaments to free-fall into the receptacles under the forceof gravity. The dimensions of the receptacles are such that the capletsor tablets become fully seated in a reasonably centered position. Afterloading, a vacuum may be applied to the support member to secure the matto the support member and to secure the medicaments to the mat, thusallowing the pallet to be inverted without the medicaments falling outof the receptacles.

The Loading Station

Empty pallets are initially located on the conveyer 100 at the arealabeled 102 in FIG. 1 with the medicament receptacle rows (231 or 271)oriented transverse to the direction of travel. The pallets are thensent to loading station 10 which is illustrated in more detail in FIG.12. The loading station 10 preferably includes a feed assembly 420 ofthe type designed for filling blister packaging with solid dosage forms.Such a feed system is available from Aylward Corp., New Bern, N.C. Thefeed assembly 420 is modified for loading the particular dimensions ofmedicaments in the desired orientation into the pallet mats utilizing anarray of modified drop tubes. Because of differences in the geometry ofthe medicaments and their respective mats 240 and 270, the caplet droptubes 300 differ in construction from the tablet drop tubes 350, but inboth cases each drop tube is long enough to hold more than onemedicament at a time.

The caplet drop tube mechanism 300, shown in FIGS. 13A-13C, is a tube ofappropriate dimensions to hold caplets 206 in a vertical orientation,i.e., with the longitudinal caplet axis in a vertical orientation. Atthe top of the caplet drop tube 300 are two guide flanges 302 mountedopposite each other. These guide flanges 302 help align the caplet 206properly as it enters the top of the drop tube 300. A pair of holdingpins 306 and 308 are located inside each caplet drop tube 300 near thebottom, one spaced vertically above the other, separated by a distanceapproximately equal to the length of a single caplet 206. These holdingpins 306 and 308 act in tandem to hold the caplets 206 in place, and torelease them one at a time into a pallet receptacle.

In operation, a pallet is first indexed under the array of drop tubes300 and a lifting device raises the pallet such that it engages thebottom of the drop tubes 300 to deposit one medicament in eachreceptacle, one medicament per drop tube 300 at a time. In a preferredembodiment, the lifting device is located below the conveyor andconsists of a plate with four locating pins in each corner. (Two pinsare located on each side of the conveyer). Bolted to the plate with thepins are two Parker slide mechanisms so as to achieve motion in twodimensions (left to right and up and down). As a pallet to be filledapproaches the load station, a pallet stop located below the conveyor istriggered. From below the conveyor, the pins are raised and guided intothe holes at each corner of the pallet. Upward motion continues, liftingthe pallet off of the conveyor until the pallet makes contact with thebottom of the drop tubes 300.

In a preferred embodiment, the bottom of each caplet drop tube 300 isshaped with chamfered portions 304. The chamfered portions 304 contactthe gripping ribs 282 of the caplet mat 270 at the drop tube receivingcompartments 274. The chamfered portions 304 cause gripping ribs 282(and consequently the caplet-holding compartments 272) to spread openslightly. (See FIGS. 14A-14B). This provides for a larger target for thecaplet 206 to enter fully into the empty caplet-holding compartment 272in a desirable position and orientation. When the pallet is lowered, thecaplet 206 is left behind in the receptacle 272.

Referring to FIG. 12, caplets 206 initially located in a supply hopper400 are controllably released and allowed to slide down a supply slide410 onto a commercial sorter assembly 430, which sorts out partial ordamaged caplets. One acceptable sorter 430 is the GMP model commerciallyavailable from the Ackley Corp. From the sorter 430, the whole,undamaged caplets 206 are sent down a second slide 432 to the feedassembly 420, described above.

In the feed assembly 420, the guide flanges 302 located at the top endsof the drop tubes 300 protrude through openings in a holding tray. Theholding tray includes a number of hills and valleys and is designed toreciprocate (oscillate) up and down. This action causes the caplets 206in the holding tray to move about the holding tray and eventually fallinto the drop tubes 300 with the correct orientation. Accordingly, it isimportant that the caplets 206 in the holding tray be sufficient innumber to fill all of the drop tubes 300, but not so great in number toimpede the motion of the caplets 206 in the tray to permit the caplets206 to fall into all of the drop tubes 300. The caplets 206 that fallinto the drop tubes 300 are then held in place by the holding pins 306and 308.

Each drop tube 300 feeds the caplets 206 one at a time by firstretracting the upper holding pin 306, thereby allowing a caplet 206 tofall towards the lower holding pin 308, which is in its extendedposition. The upper holding pin 306 is then extended to block the nextcaplet 206 in the drop tube 300 and the lower holding pin 308 isretracted, thereby allowing the first caplet 206 to free-fall out of thetube 300 and into a caplet-holding compartment 272 of the pallet below.As noted, one caplet 206 from each drop tube 300 is simultaneouslyreleased into the pallet.

The lifting device then lowers the pallet slightly, indexes to the nextadjacent row, and repeats the above process. In the describedembodiment, each pallet is loaded in two steps because the spacingbetween the drop tube center lines is farther apart than the spacing ofthe receptacles in the pallet.

For the tablets, the modified drop tube 350 shown in FIGS. 15A-15C isused. The tablet drop tubes 350 are similar to the caplet drop tubes 300but have been modified to include a J-shaped curved section 360 at thebottom of each tube 350. The J-shaped curve provides that as the tablets204 slide down the tablet drop tubes 350, they rotate 90° from avertical orientation (i.e., sidewall vertically oriented) to ahorizontal orientation (i.e., sidewall horizontally oriented). Thetablet drop tubes 350 are further modified in that the lower holding pin308 has been moved from a position in the tube above the J-shaped curve360, as in the prior art, to a place that is below the J-shaped curve360 as illustrated in FIG. 15A.

In operation, the tablet pallets are loaded in a similar manner as thecaplet pallets. Indeed, the same loading station, except for the droptubes, may be used. With reference to FIG. 12, tablets 204 initiallylocated in a supply hopper 400 are controllably released down slide 410to sorter 430, which sorts out damaged and partial tablets 204. Fromsorter 430, the whole, undamaged tablets 204 are fed to the feedassembly 420 by way of slide 432. As with the caplet drop tubes 300,guide flanges 302 located at the top ends of the tablet drop tubes 350protrude through openings in the holding tray of the feed assembly asthe holding tray reciprocates (oscillates) up and down. This causes thetablets 204 in the holding tray to fall into the drop tubes 350 with thecorrect orientation. These tablets 204 are then held in place in thedrop tubes 350 by the holding pins 306 and 308. One tablet 204 from eachdrop tube 350 is then simultaneously released into a pallet which asbeen indexed under the drop tubes 350 and raised by the lifting deviceto engage the bottom of the drop tubes 350.

The tablet loading process differs from the caplet loading process inthat there are no chamfered portions on the tablet drop tubes 350 to acton the tablet mat 240. In addition, as described above, the tablet droptubes 350 include a J-shaped curved section 360 at the bottom of eachtube 350 so that as the tablets 204 slide down the tablet drop tubes350, they rotate 90° from a vertical orientation to a horizontalorientation. However, as in the case of the caplet loading procedure,tablets 204 are loaded into a pallet in two steps, due to fact that thespacing between the drop tube center lines is farther apart than thespacing of the receptacles in the tablet mat 240. It should beunderstood that the dimensions of the medicament and the loading stationdrop tubes will determine whether more or less than two loading stepsare needed to fill a pallet.

The First Dipping Station

After a pallet is loaded, it is carried along by the conveyer 100through section 104 in FIG. 1 to the first dipping station 20. Asillustrated in FIGS. 16 and 17, each dipping station includes a palletcapture station 22, a commercial robot 24 and a dipping vat 26 full ofthe liquid coating material.

The robot system of the preferred embodiment is a Fanuc Model S-700Robot. The robot system includes a System R-J Controller with TPP andKAREL software, the specifically designed end effector tooling 23, andthe Model S-700 robot 24. The robot 24 is a series of mechanical linksdriven by servo motors, which working from the robot rotating base upthrough the end effector tooling 23, includes six axes of rotation. Thesoftware controls robot motion in all six axes as well as theinput/output that may be used between the controller and any otherdevices. Control of the robot provides for accuracy of motion to within0.001 degrees or 0.023 millimeters in terms of increments of motion athigher end motion speeds. Maximum speed of movement as measured at endeffector tooling is approximately 700 in./min.

Each capture station 22 includes an actuator mechanism for capturingpallets and loading two pallets at a time onto the end effector tooling23 of the robot 24. Appropriate pallet stops, pushing mechanisms,microswitches, linear actuators and the like are used to temporarilyretain and precisely and positively load the two pallets into thecorrect position on the end effector tooling 23. In a preferredembodiment, a pneumatically controlled pallet stop stops pallets fromentering into the capture station 22 until the previous dip cycle hasbeen completed. The pallet stop is then released allowing two pallets toadvance into the station. At the same time pallets are advancing, aslide mechanism located below the pallets is re-indexed and sets a slidefinger in an upward position to then push the two pallets onto the endeffector tooling 23. (This pushing of two pallets on also pushes two offthe end effector tooling 23 at the same time).

Referring to FIGS. 7, 11, 18 and 19, the end effector tooling 23, whichis specifically designed for the particular operation, is essentially aplatform 150 having a pair of end rails 170 along its outer edges,parallel to the direction of pallet travel. Each end rail 170 includes aslot 172 adapted to receive a corresponding edge 224 of the palletsupport member 210 (see FIGS. 7 and 11). Thus, when the end effectortooling 23 is positioned between the conveyor sections 104 and 106 inthe capture station 22 with the top surface 152 of the platform 150 atapproximately the same level as the conveyor surfaces, pallets may beindexed onto the tooling platform 150 where they are engaged by theslots 172 of the end rails 170.

The platform 150 of the preferred embodiment also has a pair of squareair bladders 154. Each air bladder 154 comprises a flat rubber liner156, approximately ½ inch wide, forming a continuous square band. Asbest seen in FIGS. 7, 11 and 19, the rubber liners 156 are held in placeby inner and outer frames 158, 160, between which are channels 162 inthe platform 150 for communicating air pressure throughout the rubberliners 156. Each air bladder 154 is positioned on the platform 150 toalign with the periphery of one of the pallets when properly indexed onthe platform 150. Thus, after two pallets have been indexed onto theplatform 150, the air bladders 154 are pressurized to inflate slightlyand push on the underside of the corresponding pallets at a smoothregion 226 which forms a continuous square ring inboard of the peripheryof the pallets. The pallets are thereby frictionally secured to the endeffector tooling 23 between the pressurized bladders 154 and the slots172 in the side-rails 170. (See, FIGS. 7 and 11). The air bladders 154also function to form a positive seal with the pallets for theapplication of a vacuum, as described below.

The end effector tooling 23 also houses a pair of eductors 168 mountedto the underside of the platform 150. The eductors 168 take compressedair and convert that energy into a vacuum. One acceptable eductor 168 iscommercially available from PIAB.

In operation, pallets are indexed onto the tooling platform 150 fromconveyor section 104 two at a time by a servo driven slide tab. The airbladders 154 are then pressurized to secure the pallets to the tooling23 and the eductors 168 are activated to apply a vacuum to the bottom ofpallets. As best seen in FIG. 18, the vacuum is applied throughapertures 164 located in the tooling platform 150. One vacuum aperture164 is centrally located within each of the areas defined by the airbladders 154. In addition, two vacuum distribution channels 166 areformed in the platform 150 perpendicular to each other and intersect atthe vacuum aperture 164. The vacuum is communicated through four holesin each pallet support member 210 to act on the rubber mat 240 or 270positioned thereon to secure the medicaments to the pallet, aspreviously described. The robot 24 then extracts the pallets (withvacuum on) from their position in the conveyor system 100 and moves themto the dipping vat 26.

Upon completion of the dip cycle (described below), the pallets arereturned to the capture station 22 by the robot arm 24. The vacuum isthen deactivated and the air bladders 154 are depressurized. Thejust-dipped pallets are then urged off of the tooling platform 150 andonto the next conveyor section 106. The next two pallets, which havebeen queued up, may then be indexed into the tooling platform and theprocess repeated. The robot does not control the end effector tooling 23except for positioning. The actuation of the vacuum on/off, and settingconditions under which the robot can start and stop its cycle, iscontrolled by the main programmable logic controller of the carrierhandling system (described below).

When coating caplets, each capture station 22 optionally may include acentering plate 28 having a series of countersunk holes 29. This plate28 may be used to center and orient axially the caplets to ±5° vertical.FIG. 19 illustrates how the centering is obtained by using the robot armend effector tooling 23 to engage the two pallets and raise the palletsvertically against the centering plate 28 so that the caplets engage thecorresponding holes 29. The pallets are urged against the centeringplate 28 with a vacuum being applied so as to hold the caplets in aproperly oriented position. When coating tablets, this step is generallynot necessary. It also may be omitted for caplets depending on the sizeof the caplets and the dimensions of the receptacles. Further, thecentering plate 28 could alternatively be lowered onto the pallets andthen raised after the centering operation.

The dipping vat 26 contains the first coating which in the preferredembodiment is a white gelatin coating. The robot 24, after withdrawingtwo pallets from the pallet capture station 22, and, in the case ofcaplets, optionally centering them using the centering plate 28, invertsthe pallets with the vacuum engaged and dips the medicaments into thegelatin bath, using precisely controlled times and rates for lowering,holding and raising the medicaments. FIGS. 20 and 21 show caplets andtablets, respectively, being dipped by the currently preferredembodiment. As illustrated, the medicaments are dipped into thegelatinous bath to coat slightly more than half the medicament.

The speed with which the medicaments are lowered and raised from thegelatin, the amount of time the medicaments are held in the gelatin, andthe gelatin temperature and viscosity, are particularly important toensure that the medicament is covered by the gelatin to the desireddegree and with the desired coating thickness, and migration is kept toa minimum when the pallet is returned to an upright orientation. Thecurrently preferred gelatin (described below) is maintained at atemperature range of 120-130° F. and has a viscosity of from 400 to 625centipoise. It has been found that the parameters listed in Table 2yield the most desirable results for a gel temperature of 124° F. foryellow and white and 127° F. for red, and viscosity of 400-600centipoise. Table 3 contains the presently preferred parameters for thefirst dipping station 20, as well as the second dipping station 60(described below).

TABLE 2 DIPPING PROFILE RANGES MOVEMENT VARIABLE RANGE OF VALUESApproach Rate (in/min) 550-650 Approach Dwell (sec) 0.0-2.0 Dip Rate(in/min) 30-45 Dip Dwell (sec) 0.0-4.0 Withdrawal Rate (in/min) 4.5-7.5Withdrawal Dwell (sec) 0.0-1.5 Departure Rate (in/min) 550-650 DepartDwell (sec) 0.0-3.0

TABLE 3 PREFERRED DIPPING PROFILES FIRST DIPPING SECOND DIPPING FIRSTDIPPING SECOND DIPPING STATION 325 mg STATION 325 mg STATION 500 mgSTATION 500 mg MOVEMENT VARIABLE CAPLET (WHITE) CAPLET (YELLOW) CAPLET(WHITE) CAPLET (RED) Approach Rate (in/min) 600 600 600 600 ApproachDwell (sec) 0.0 0.0 0.0 0.0 Dip Rate (in/min) 40.0 35.0 40.0 40.0 DipDwell (sec) 1.0 1.0 1.0 1.0 Withdrawal Rate (in/min) 6.0 6.0 6.9 5.5Withdrawal Dwell (sec) 0.5 0.5 0.3 2.0 Departure Rate (in/min) 600 600600 600 Depart Dwell (sec) 0.0 0.0 0.0 0.0 Invert Dwell (sec) 1.0 1.01.0 1.0 Slide accel/decel (in/sec²) 80 100 150 150 Slide Speed (in/min)55 65 85 85 Slide Initiation (sec) 2 2 2 2

Referring to Tables 2 and 3, once the medicaments have been positionedover the dipping vat in an inverted orientation, they are loweredtowards the gelatin coating by the robot arm 24 at the indicated“Approach Rate” until they are just above (i.e., about ⅛ inch above) thefluid level in the dipping vat 26 where they remain for the indicated“Approach Dwell” time. The medicaments are then lowered at theprescribed “Dipping Rate” into the gelatin coating until they reach thedesired dip depth and allowed to remain partially submerged for theindicated “Dip Dwell” time. The medicaments are then raised from thegelatin coating at the listed “Withdrawal Rate” to a point where the endof the medicament has just passed the fluid surface, i.e., 0.005″-0.010″above the fluid level, and held in place above the gelatin bath for the“Withdrawal Dwell” time. The medicaments are next raised further fromjust above the gelatin bath, at the indicated “Departure Rate”, to theinitial position, where they remain at rest for the “Departure Dwell”time before being inverted to their upright orientation. After beingreturned to their upright orientation, the medicaments remain inposition above the dipping vat 26 for “Invert Dwell” time and are thenreturned to the capture station 22 by the robot arm 24.

The “Slide accel/decel” rates listed in Table 3 are the acceleration anddeceleration rates of the slide which pushes the pallets onto the endeffector tooling 23 of the robot arm 24. Similarly, “Slide Speed” is thespeed of the pallet indexing slide at the end of the acceleration cycle.If either of these values is improperly set, the medicaments could bedislodged from the pallets when being indexed onto or removed from theend effector tooling 23. The “Slide Initiation” is the time requiredbefore the slide motion can be initiated. This time is required, forexample, to clear the pallets on the end effector tooling 23 before asubsequent pair of pallets can be loaded onto the tooling 23.

These parameters provide for a rapid chill set of the gelatin coatingwith minimal runback as the medicaments are extracted from the bath andinverted 180° to the coated side up position. They advantageously avoidthe need for dabbing the medicaments to remove excess gelatin at thebottom of the medicaments, and for additional angular movement, e.g.,360° rotation about the longitudinal axis or the plane of the pallet,thereby reducing the processing steps required.

At the conclusion of the first dipping sequence, the robot 24 restoresthe two pallets to the upright orientation and returns them to thecapture station 22, where the vacuum is turned off and the air bladders154 are depressurized. The capture station 22 then operates amicroswitch and uses a pushing mechanism (e.g., a pusher tab mounted ona servo driven slide) to release and push controllably the next twopallets, which may have been backed up on the conveyor, into the capturestation 22, thereby ejecting the two just-dipped pallets out of capture.station 22 and onto the following conveyor section 106. Thus, the nexttwo pallets are loaded into the capture station 22 of the dippingstation 20.

The Dryer Station

The just-dipped pallets advance along the conveyor 100 through section106 in FIG. 1 into the dryer loading area designated at 32. The palletsare then transferred in groups of four onto a dryer conveyor 100 a thatadvances the pallets four abreast through the dryer station 30. Thedryer station 30 includes two drying rooms 34 and 36 separated by awall, with each room having two parallel 40 foot long dryer conveyorsrunning through it, one conveyor for first pass drying and the secondfor second pass drying (described below). Thus, on each pass themedicaments travel through 80 feet in total.

As the pallets are advanced through the dryer station 30, they passunder air plenum plates 42, each of which has a plurality of apertures44 through which a downward air flow is directed. The plates are ⅛ inchthick and are disposed approximately 1 to 1½ inches above themedicaments. Each aperture 44 is {fraction (3/32)} inch in diameter witha {fraction (1/16)} inch countersink on the air supply side. Using theprocess air handling system described below, this results in a jetvelocity through each aperture 44 of approximately 8,000 feet perminute.

In the currently preferred embodiment, the air flow apertures 44 in theplates 42 are arranged in a plurality of sinusoidal rows 46, eachrunning in the direction of product flow. FIG. 22 is a partial top viewof an air plenum plate 42 illustrating the arrangement of air flowapertures 44. The apertures are longitudinally spaced at intervalsapproximately {fraction (15/16)} of an inch from each other in thedirection of product flow. Apertures in adjacent rows are laterallyspaced approximately ¾ of an inch apart. To form a sinusoidal-likearrangement, the holes in each row are offset laterally from a commonline by varying distances. Looking at FIG. 22 from left to right, theholes in each row are offset by 0, {fraction (6/16)}, {fraction (9/16)}and {fraction (3/16)} inches (for an amplitude A of {fraction (9/16)}inches), which pattern repeats itself every 3¾ inches (for a period P of3¾ inches).

In the currently preferred embodiment, it is desirable to provideapproximately one sinusoidal row 46 of apertures 44 for each row (231 or271) of medicaments on the pallets as they pass below. Since the spacingbetween adjacent caplet compartment rows 271 and between adjacent tabletreceptacle rows 231 is approximately equal to each other and to thespacing of the sinusoidal air aperture rows 46, this is accomplished bypassing the pallets through the dryer sections with the medicament rows(231 or 271) oriented in the same direction as the product flow. As aresult of the high air velocity and sinusoidal aperture arrangement,each medicament passes through numerous high speed air swirls as ittravels linearly through the dryer tunnel. This results in quick uniformdrying of the entire coated medicament surface.

The first and second dryer rooms operate at essentially the sameconditions which are 34° C. dry bulb 18° C. dewpoint, nominal, with thetotal airflow from the air plenums being sufficient to generate a fiveinch static pressure (approximately 22,500 cubic feet per minute in eachroom). By contrast, the ambient temperature and humidity of the room inwhich the CHS is located is typically maintained at 72±5° F. and 50±5%relative humidity. The moisture driven off of the medicaments isexhausted by a process air exhaust system. FIG. 23 is a schematicdiagram of the presently preferred process air flow handling system.

Approximately 10% (4,500 cubic feet per minute) of the total process airrequirement is drawn from outside (or inside) of the building by amake-up air handling unit 120. This air passes through a commerciallyavailable air handler that features a pre-filter and filter section, andheating and cooling coils. Air is then drawn into a commerciallyavailable fan and the fan's discharge is equally split to deliver thepre-conditioned air (constant drybulb and dewpoint temperatures) to twoprocess air handling units 122. This is a once through system.

Supply air from the make-up air handler 120 and return air from thedrying room is mixed and drawn into the suction side of a commerciallyavailable unitary air handling units (process air handling units) 122.In the process air handler 122, air passes through a pre-filter andfilter section for removal of gross particulate. Air then passes throughheating and cooling coils to temper the air to the desired dry bulbtemperature for drying the product. Air is then drawn into acommercially available fan that has a discharge capacity of 22,500 cubicfeet per minute.

After the fan, moisture is introduced into the air stream to provide thedesired dewpoint delivered to the product.

The dry bulb and dewpoint conditioned air then travels through thedelivery ductwork to then feed the air delivery plenums 40 directly overthe exposed product in the dryer rooms 34 and 36. Inside the plenums 40,air passes through final high efficiency particulate air (HEPA) filtersfor particulate removal then passes through the air plenum plates 42which provide the impingement drying of the product. The static pressureof the system is measured between the HEPA filters and the plenum plates42. After the drying, the air is then drawn back to the suction side ofthe process air handler to repeat the process.

Each of the two drying rooms are connected to an exhaust fan 124 thatextracts air and drives off moisture from the space. The amount of airexhausted is dependent on the amount of air delivered by the make-up airhandling unit 120. (Typically, the volume of air exhausted is greaterthan that supplied by the make-up air handling unit so as to keep thedrying room under a negative pressure relative to the CHS area).

After passing through the two dryer rooms 34, 36 the pallets areadvanced to the exit area, designated 38 in FIG. 1. At area 38, the fourpallets are held against a stop, and then transferred onto the nextconveyor section 108 in groups of four. The four pallets then advance tothe reorientation station 50 where they are stopped, held and flippedone pallet at a time.

The pallets are advanced through the dryers at approximately 2.5 feetper minute. Thus, it takes approximately 32 minutes to pass through both40 foot rooms. Typically, each group of four pallets is spaced between12 and 13 inches from the preceding group, and contains 1008 medicaments(252 tablets per pallet). This provides a throughput of from 60,000 to90,000 medicaments per hour, assuming no waste.

The Reorientation Station

The reorientation station 50, which is illustrated in FIGS. 24-26,includes a reorientation mechanism 59 which is essentially a drummounted to rotate about a horizontal axis. The rotation of the drum isdriven by a pneumatic motor capable of clock wise and counter-clock wiserotation, which is connected by a toothed belt to the drum assembly andcontrolled by the computer system described below.

The reorientation mechanism 59 houses two lift plates 51 for receivinglike pallets in opposition, and a transfer plate 53 interposed betweenthe lift plates 51. Each lift plate is supported by four pilot rods 58along which guide bushings Sa slide to allow vertical movement of thelift plates 51. Two pneumatic lift mechanisms 56 are secured to oppositesides of the body of the reorientation mechanism 59 with one liftmechanism 56 connected to each lift plate 51 so as to urge the liftplate vertically along the pilot rods 58. Each lift plate 51 alsoincludes end rails 52, similar to the platform end rails 170 of thedipping station. The end rails 52 are mounted along the edges of thelift plates 51, parallel to the direction of pallet travel. Like endrails 170, end rails 52 include slots adapted to receive the edge 224 ofthe pallet support member 210.

The transfer plate 53 includes an array of apertures 54 which correspondto the medicament receptacles of the pallets for transferring themedicament from one pallet to the other. (See FIGS. 25-26). In addition,when coating caplets, the transfer plate 53 of the preferred embodiment,illustrated in FIG. 25, includes chamfered protrusions 55 similar to thechamfered ends 304 of the caplet drop tubes previously described. Thechamfered protrusions 55 are located on both surfaces of the transferplate adjacent to the apertures 54 in positions corresponding to thedrop tube receiving compartments 274 in the caplet mats 270.

In operation, the pallet to be unloaded is indexed onto thereorientation mechanism 59 and secured to the lower lift plate 51 by endrails 52 by a stop and slide mechanism similar to that in the capturestation 22 of the dipping station 20. An empty pallet is already locatedon the upper lift plate 51 in an inverted (i.e., medicament receptaclesdown) orientation. The loaded pallet is then urged against the transferplate 53 by lift mechanism 56 and aligned with the empty pallet and thetransfer plate 53 by way of alignment pins 57 which engage the cornersof each pallet support member 210 at alignment holes 222 (see FIG. 3).When coating caplets according to the preferred embodiment, thechamfered protrusions 55 on either side of the transfer plate 53 contactthe gripping ribs 282 of the caplet mats 270 at the drop tube receivingcompartments 274 thereby causing the gripping ribs 282 (and consequentlythe caplet-holding compartments 272) in both pallets to spread openslightly. This allows for a larger target for the caplet to enter theempty pallet and eases the exit of the half coated caplet from theloaded pallet. It also can act to break a gelatin-mat seal, if one hasformed.

The reorientation mechanism 59 is then rotated 180° in a firstdirection. As a result, the half-coated medicaments fall through thetransfer plate apertures 54 into the empty pallet, which is now in thelower position, under the force of gravity. The now loaded pallet(located on the lower lift plate 51) is then moved away from thetransfer plate 53 and pushed onto the conveyer by, e.g., a followingloaded pallet to be unloaded. For the next pallet, the same sequenceoccurs except that the reorientation mechanism 59 rotates 180° in theother direction. The back and forth rotation is used for simplicity ofhydraulic (pneumatic) and electronic control and wiring.

In coating different sized products, different transfer plates 53 may berequired (e.g., 500 milligram caplets may require a transfer plate 53with larger apertures 54 than 325 milligram caplets). For tablets, thetransfer plate 53 may be omitted as shown in FIG. 26, in which case thetwo pallets are urged against each other in the reorientation mechanismprior to being inverted. Preferably, however, a relatively thin transferplate (not shown) is used for tablets to ensure a centered transfer.

In the preferred embodiment, only the transfer plate 53 need be changedfor different medicament products, rather than having to use multiplereorientation mechanisms 59. This saves time and makes it significantlyeasier to reconfigure the system in preparation for coating differentproducts.

The Second Dipping Station

After reorientation, the pallet with the array of medicaments havingtheir uncoated ends facing upwards is then transported by conveyersystem 100 to a second dipping station 60. The second dipping station 60operates in the same manner as the first dipping station 20, except thata different coating material may be applied. In the currently preferredembodiment, the second coating is either a white, red or yellow gelatincoating, depending on the size of the medication and whether one coloror two color medicaments are desired. Optionally, a single dippingstation may be used, for example, so as to coat the medicaments with asingle color. Alternatively, two dipping vats 26 could be supplied froma single gelatin supply (tanks 80 and 90).

In the preferred embodiment, the medicaments are dipped into thegelatinous bath according to the profile listed in Tables 2 and 3(above). At the first dipping station, caplets are dipped to a depth ofapproximately ½ the caplet length plus 0.015″-0.020″ and at the seconddipping station, they are dipped to a depth of approximately ½ thecaplet length. The extent of dipping of each “half” can be controlled toachieve coverage which extends from no overlap between the first andsecond coating, to some overlap which is not visible to the eye and maynot be felt, to a substantial overlap which provides a surfacediscontinuity which can be felt and/or seen.

It should be understood that the first and second dipping profiles canbe selected to obtain the desired coating, ranging from no overlap,abutting coatings, and overlapped coatings. When combined with theviscosity of the gelatinous baths, the configuration and thicknessprofile of the gelatin coating on the medicaments can be selected asdesired. For example, both coatings can be of the same viscosity andproduce the same thickness.

The Second Pass Through the Dryer Sections

After the second coating has been applied, the pallets are againadvanced through both rooms 34 and 36 of the dryer station 30, this timepassing through the second tunnel. The pallets travel in the samedirection as occurred after the first coating and under the sameconditions, again four pallets abreast at a time. At the exit 38 of thesecond dryer section 36, the medicaments are fully dried and ready forunloading. Before unloading, however, it may be desirable to subject thefully coated and dried medicaments to a curing step, the curing stepbeing substantially identical to the conditioning that was employedafter the subcoating was applied.

The Unloading Station

Unloading preferably occurs one pallet at a time at station 70. Theunloading station 70, illustrated in FIGS. 27 and 28, captures a palletat capture station 71 and indexes it under an unloading plate 73 andunloading cone 76. Unloading plate 73 retains the mat 240 or 270 in itsplace against support member 210 as the pallet is inverted to dischargethe coated medicaments into unloading cone 76.

In a preferred embodiment, the unloading cone 76 is connected to theunloading plate 73, such that they pivot about a common axis as thepallet of medicaments is raised from the capture station 71 andinverted. This minimizes the risk of ejecting the medicaments or havingthe medicaments fall out of the pallet so as to become waste during theunloading operation. The unloading cone 76 and unloading plate 73 aredriven about the pivot axis by a pneumatically actuated motor capable ofrotating clock wise and counter-clockwise.

In operation, a pneumatically actuated pallet stop allows the loadedpallets to enter the capture station 71 one at a time. The palletentering the station slides in between two spring loaded carrier guides62 which include slots 64 to engage the perimeter of the pallet in asimilar manner to that in the reorientation station 50. Once the palletis in the correct position, the motor is actuated to rotate the unloadmechanism. Starting the rotation of the unload mechanism causes the twospring loaded carrier guides 62 to “pull up” the pallet so as tocompress the pallet against the unloading plate 73. The pallet, alongwith the plate 73 and cone 76 are then flipped over to strike stopmember 78. This angular momentum is thus rapidly decelerated, whichejects the coated medicaments into the unloading cone 76.

In one embodiment, the unloading plate 73 is similar to the transferplate 53 previously described. Like the transfer plate 53, the unloadingplate 73 may include a plurality of apertures 74 which correspond to themedicament receptacles of the pallets. In addition, when unloadingcaplets, the unloading plate 73 may include chamfered protrusions 75(see, FIG. 28) in a similar arrangement to that found on the transferplate 53. Unlike the transfer plate 53, however, the chamferedprotrusions 75 of the unloading plate 73 are only required on one side,the side facing the pallet to be unloaded. In operation, the chamferedprotrusions 75 on the unloading plate 73 contact the gripping ribs 282of the caplet mat 270 at the drop tube receiving compartments 274,thereby causing the caplet-holding compartments 272 to spread openslightly. This breaks any adhesion formed between the gelatin and mat,and also allows the fully coated caplet to free-fall under the influenceof gravity out of the pallet, minimizing the force used to rotate thepallet against the stop member 78.

In another embodiment, the unloading plate 73 has a mesh screen or gridwhich contacts a certain number of receptacles, but not everyreceptacle. For example, a grid that contacts every row and every thirdcolumn of the pallet is suitable.

Once the fully coated medicaments are ejected from the inverted palletinto unloading cone 76, they fall through the opening 77 and onto adiverter 79 which directs the unloaded medicaments into either acollecting container or a refuse container. The diverter 79 isessentially a short chute which is rotatable between two positions, thefirst (shown in FIGS. 27 and 28) to direct the medicaments into thecollecting container, and the other (shown in phantom in FIG. 28) todirect the medicaments into the refuse container. The diverter 79 iscontrolled by the computer system described below to selectively rejectdefective batches. Medicaments which are not rejected are collected inthe collecting container and taken to be packaged as the finishedproduct.

The now empty pallet is then returned to an upright orientation, theunloading plate 73 is raised and the pallet is pushed onto the nextconveyor section 102, which was the initial starting position for thepallet. For the next pallet, the same sequence occurs. The unloadedpallets are transported to the loading station by the conveyer system100 and the entire process is repeated.

The Automatic Drawdown System (ADS)

The ADS provides the two supplies of coating material, one for eachdipping station. Referring to FIGS. 1 and 29, a batch of coatingmaterial is first made in each of the large tanks 80, which is thentransferred into the respective smaller holding tanks 90. Holding tanks90 are continuous flow tanks that continuously feed the dipping vats 26.A holding tank 90 is periodically refilled from a large tank 80 whenevera new batch is provided or whenever another volume of coating materialis needed to continue production. A clean-in-place system is used toclean out tanks 80 (including the associated piping, pumps and hoses)after a batch is made, and the whole dipping system (tanks 80 and 90,and vats 26) at the end of a production run.

In the preferred embodiment, the medicaments are coated with agelatinous material. The gelatinous material includes water, gelatin,glycerin, a plasticizer, a surfactant and preservatives. The currentlypreferred gelatin formulations, along with the tested ranges, are givenbelow in Table 4, with the balance of the mixture in each case beingmade up of purified water.

It should, of course, be understood that one of ordinary skill in theart of gelatin use in the pharmaceutical industry would be able todetermine equivalents without undue experimentation, given thedisclosure provided. For example, other known plasticizers, such aspolyethylene, glycols, triacetin, mineral oil or caster oil, may be usedin place of titanium dioxide. Likewise, other known surfactants, such asSpan or Tween, may be used instead of sodium lauryl sulfate. Further, asindicated in Table 4, various dyes may be added to impart color to thegelatin.

TABLE 4 GEL FORMULATIONS % of RM Tested Preferred Red White Yellow RawMaterial Range Range Gelatin Gelatin Gelatin Gelatin 25-40 28-30 29.1629.16 29.17 Glycerin  2-10 4 3.65 3.65 3.65 FD&C Red 1.82 FD&C Yellow.83 Titanium Dioxide   1-3.5 1.5 1.37 1.37 1.37 Sodium Lauryl Sulfate.2-.6 .3 .27 .27 .27 Methylparaben   0-.44 .44 .44 .44 Propylparaben  0-.04 .04 .04 .04 Butylparaben   0-.02 .02 .02 .02

The process for making the gelatin is computer controlled with operatorinputs required. Water is added to tank 80, along with the gelatin,coloring, preservatives, and other materials, as indicated. The gelatinis hydrated and mixed under a vacuum of about 29 inches of mercury forthirty minutes. The heat is then turned on to melt the hydrated gelatinat a temperature of 104° to 108° F. for approximately forty-fiveminutes, being careful not to boil the solution.

After the melting, the vacuum is broken and tank 80 is heated to atemperature below 140° F., preferably between 120° and 130° F. Once thetemperature matches that of the smaller holding tank 90, the batch istransferred into the holding tank 90. The holding tank 90 continues tocirculate the warm gelatin into the dipping vat 26 through feed valve 27located near the bottom of dipping vat 26. Overflow is captured byoverflow vat 25 and returned to tank 90 via gravity and vacuum assist tobe mixed with the rest of the batch. This arrangement maintains aconstant gelatin level in dipping vat 26 and provides for uniformgelatin consistency. Tank 90 is maintained at a low vacuum, about 30inches of water, in order to degas the circulating gelatin. Heatexchangers are used to maintain temperature and a peristaltic pump (notshown) is used to inject water to compensate for water loss due toevaporation.

Computer Control

A network of Man Machine Interface (MMI) industrial computers are usedto monitor and control the operation of the entire system. Each computeris allowed to directly control the apparatus within a local area, i.e.,within the operator's field of view, and otherwise is capable ofmonitoring all other systems operating conditions. This allows anoperator to view what is going on in a different room, but not tocontrol it.

Each pallet is provided with a bar code or other identifying indicia,which is scanned as the pallet enters each station. This provides thesystem with the ability to monitor the process and track and identifyany problem that may occur at the various processing stations. Thus, ifa given step in the process is defective, when the pallet gets to theunloading station, the diverter 79 is actuated to divert the unloadedmedicaments into a separate waste container. Similarly, if there was adetected problem with some other part of the process that is out oftolerances for the process, then certain subsequent process steps willbe skipped. For example, if there was a problem with the first dippingstation 20, then the pallet will not be reoriented or dipped a secondtime, but it will be unloaded and the contents diverted as waste.Indeed, the pallet may pass directly through the reorientation station50 if so desired. Further, appropriate programming and scanning of barcodes can allow one robot 24 to be used to dip the pallets in theappropriate one of two or more dipping vats 26.

The present invention has been described in terms of preferredembodiments thereof. Other embodiments, features and variations withinthe scope of the invention will, given the benefit of this disclosure,occur to those having ordinary skill in the art.

What is claimed is:
 1. An apparatus for drying a plurality of dip-coatedmedicaments, said apparatus comprising: an air plenum having at leastone air directing plate, said at least one air directing plate having atleast one row of air directing apertures arranged in a sinusoidallayout; an air source for providing air to said at least one airdirecting plate; and a dryer conveyer system for transporting saidmedicaments under said air plenum in a product flow direction.
 2. Theapparatus of claim 1 wherein said at least one row of air directingapertures is oriented substantially parallel to said product flowdirection.
 3. The apparatus of claim 2 further comprising: at least onepallet, said at least one pallet comprising at least one row ofmedicament receptacles; wherein said dryer conveyor system transportssaid medicaments such that said at least one row of medicamentreceptacles are maintained parallel to said at least one row of airdirecting apertures.
 4. The apparatus of claim 3 wherein said at leastone row of air directing apertures includes one row of air directingapertures for every one of said at least one row of medicamentreceptacles.
 5. The apparatus of claim 2 wherein the apertures arespaced at intervals of approximately {fraction (15/16)} inch in theproduct flow direction.
 6. The apparatus of claim 1 wherein said dryerconveyer system transports said plurality of pallets under said airplenum at a distance of approximately 1 to 1½ inches under said airdirecting apertures.
 7. The apparatus of claim 1 wherein each of saidair directing apertures have a diameter of approximately {fraction(3/32)} of an inch.
 8. The apparatus of claim 1 wherein the sinusoidalrow of apertures has an amplitude of approximately {fraction (9/16)} ofan inch.
 9. The apparatus of claim 1 wherein the sinusoidal row ofapertures has a period of approximately 3¾ inches.
 10. The apparatus ofclaim 1 wherein each air directing aperture directs a jet of air havinga jet velocity of approximately 8,000 feet per minute.
 11. The apparatusof claim 1 wherein said at least one row of air directing aperturescomprises a first and a second row of air directing apertures, whereinapertures in said second row are spaced approximately ¾ inch laterallyfrom apertures in said first row.
 12. The apparatus of claim 1 furthercomprising at least one dryer room, wherein said air directing aperturesopen into said at least one dryer room and said dryer conveyor systemtransports medicaments through said at least one dryer room.
 13. Theapparatus of claim 12 wherein said at least one dryer room comprises: afirst dryer room; and a second dryer room proximate said first dryerroom, wherein the dryer conveyor system transports said medicamentsthrough both said first and said second dryer rooms.
 14. The apparatusof claim 12 further comprising means to maintain said at least one dryerroom at 34° C. dry bulb and 18° C. dew point.
 15. An apparatus fordrying a plurality of dip-coated medicaments, said apparatus comprising:means for transporting said medicaments in a product flow direction;means for providing a flow of air; and means for directing said flow ofair at said medicaments as they are transported in the product flowdirection by the transport means, said air directing means includingmeans for producing a plurality of air jets in at least one sinusoidalarrangement.
 16. The apparatus of claim 15 wherein said at least onesinusoidal arrangement of air jets is oriented in the product flowdirection.
 17. The apparatus of claim 15 further comprising means forsupporting said medicaments in at least one row as they are transportedby said transport means, wherein said transport means maintains said atleast one row of medicaments substantially parallel with said productflow direction.
 18. A method for drying a plurality of dip-coatedmedicaments, said method comprising: transporting said medicaments in aproduct flow direction; producing a flow of air; and directing said flowof air at said medicaments in a sinusoidal arrangement of air jets asthe medicaments are transported in said product flow direction.
 19. Themethod of claim 18 wherein said step of directing said flow of air atsaid medicaments comprises directing said flow of air in a sinusoidalarrangement of air jets oriented in the product flow direction.
 20. Themethod of claim 19 further comprising: supporting said medicaments in atleast one row as they are transported; and maintaining said at least onerow of medicaments substantially parallel with said product flowdirection.